Impact test behavior of aluminum alloys welded joints: Experimental and numerical analysis

Abstract

The Charpy impact test behavior of base metal, weld metal, and heat‐affected zone for 6061‐T6 and 7075‐T651 aluminum alloy welds was analyzed. Force versus time curves of welded joints were obtained by means of an instrumented Charpy pendulum. An explicit finite element model was implemented to evaluate the performance of the Cowper–Symonds constitutive model. Parameters were obtained through a strain‐rate‐sensitivity analysis of base metals at high strain rates. Experimental results were compared with those computed by finite element method (FEM) by assuming the same physical and geometrical conditions of the dynamic‐experimental tests. ANSYS‐LS DYNA was used to achieve the FEM simulations. The comparison between experimental and FEM results in terms of force versus time data was evaluated. Higher accuracies were observed in Al 7075‐T651 alloy (roughly 98%). The 6061‐T6 alloy has shown an approximation of about 90%. Discrepancies are explained in terms of the effective plastic strain at fracture.

Measuring J‐R curve under dynamic loading conditions using digital image correlation

“…10 Such loading rates are sufficient to alter the hardening characteristics of the test material, without inducing significant inertia effects on the cracked body. 11 The Charpy test 12 and the drop-weight tearing test (DWTT) 13 are the two most frequently adopted laboratory tests to assess the fracture toughness under dynamic loadings. The Charpy test is more suitable for the assessment of low-toughness materials, while the DWTT is better for materials with higher toughness.…”

Modification of the Johnson–Cook model for metal at a wide range of strain rates and application in the dynamic response of honeycomb panels

“…However, JC model assumes that strain hardening effect and strain rate effect are mutually independent, so it can not accurately describe the coupling phenomenon between strain hardening effect and strain rate effect. Zhang et al [13] and Wang et al [14] improved the strain rate effect term of JC model and improved the defect that the original JC model could not describe the strain rate dependence of yield stress; Meng et al [15] replaced the strain rate term of JC model with the strain rate effect term of Cowper Symonds (CS) constitutive model which can reflect the coupling effect of material strain rate and plastic deformation under [16][17][18] impact test, and obtained JC-CS model which can better express the strain rate strengthening effect. Xu et al [19] improved the strain hardening term of JC model and improved the accuracy of the model, but the model curve tends to be linear and does not conform to the stress-strain relationship of metal material deformation.…”